US power utility Arizona Public Service (APS) has unveiled plans to install 850 MW of electricity storage by 2025, including 450 MW that will come onstream by 2021 and an additional 400 MW slated for commissioning by 2025. It also expects to install at least 100 MW of new solar generation capacity by this date. The new storage capacity will be deployed in several locations and will be assigned either to support the upgrade of existing large-scale solar plants in Maricopa and Yuma counties (Arizona, US) by 2020 (200 MW) or will be built under the framework of new combined solar-storage plants (500 MW of solar storage and stand-alone battery storage by 2025). APS will also use 150 MW of solar-fueled battery storage to meet peaking demand.
APS' storage plan is currently one of the largest battery storage announcement in the United States. Another key project of this kind was unveiled by the Californian utility Pacific Gas and Electric (PG&E) in July 2018. It consists of several lithium-ion (LiOn) battery energy storage projects with a total storage capacity of 567.5 MW/2,270 MWh. They include in particular a 300 MW/1,200 MWh LiOn battery project developed by Dynegy (Vistra Energy) and a 182.5 MW/730 MWh battery project owned by PG&E and developed by Tesla, under an engineering, procurement and construction (EPC) contract. These two projects will be built in Moss Landing, one of California's most transmission-constrained region.
Energy storage will play an increasingly important role in the US and the recent decreases in battery prices are enabling it to gradually become a competitive alternative to traditional solutions. Its development is expected to help the utilities to enhance overall power grid reliability and integrate renewable energies such as solar power.